Microscope provided with an objective lens focusing apparatus and an objective lens switching apparatus

ABSTRACT

A microscope is provided which includes a frame main body having a base portion, an objective lens switching mechanism, a stage, and an ocular lens for observing a specimen image obtained with one of the objective lenses. A rough/fine motion focusing mechanism is disposed rearward of the stage, for moving the objective lens switching mechanism along the observation optical axis in rough motion and fine motion. A first rough motion handle and a first fine motion handle are provided near the rough/fine motion focusing mechanism, for operating the rough/fine motion focusing mechanism. A rough/fine motion focusing operation portion is provided for operating the rough/fine motion focusing mechanism and includes a second rough motion handle and a second fine motion handle provided near a front end of the base portion. And a linkage mechanism is provided for linking the rough/fine motion focusing mechanism with the rough/fine motion focusing operation portion.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a Divisional application of U.S. application Ser.No. 09/906,269, filed on Jul. 16, 2001, now U.S. Pat. No. 6,906,858,which is based upon and claims the benefit of priority of the priorJapanese Patent Application No. 2000-216190, filed Jul. 17, 2000, theentire contents of which is incorporated herein by reference. Thisapplication is also based upon Japanese Patent Application No.2000-336170, filed Nov. 2, 2000, the entire contents of which isincorporated herein by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to improvement of a microscope providedwith an objective lens focusing apparatus and an objective lensswitching apparatus, and more particularly to improvement of anobjective lens focusing apparatus which moves an objective lens or astage in the microscope and an objective lens switching apparatus whichis employed in the same microscope and provides such a function asmagnification switching.

2. Description of the Related Art

Generally, the microscope includes an objective lens focusing apparatusfor moving an objective lens to focus on a specimen and an objectivelens switching apparatus for switching a plurality of the objectivelenses to place one of them selectively on an observation optical axis.

As the focusing mechanism, there are two types, namely one type in whichthe objective lens is moved upward or downward (hereinafter referred toas up/down) along the optical axis and another type in which a stagesupporting a specimen is moved up/down, in order to adjust a distancebetween the specimen and the objective lens or the stage. Generally, thefocusing apparatus is provided with a rough motion handle and a finemotion handle. In this focusing apparatus, if the rough motion handle isrotated, a rotation of this rough motion handle is transmitted to arough motion shaft, and further the rotation is transmitted to a pinionand rack and transformed to a vertical motion. Consequently, theobjective lens is moved in rough motion in any one of the verticaldirections along a guide.

If the fine operation handle is rotated, a rotation of the fine motionhandle is decelerated by a reduction gear or the like and transmitted tothe rough motion shaft. This rotation is transmitted to the pinion andrack gears and transformed to a vertical motion, so that the objectivelens is moved in fine motion in any one of the vertical directions alongthe guide.

Therefore, even if the rough motion handle and the fine motion handleare rotated by the same rotation amount or by the same rotation number,the moving amount of the objective lens due to the operation of therough motion handle is larger than the moving amount of the objectivelens due to the operation of the fine motion handle. When the roughmotion handle is operated, the objective lens is moved in rough motion,while when the fine motion handle is operated, the objective lens ismoved in fine motion.

The rough/fine motion handle of the focusing apparatus is provided on abottom side thereof, away from the front side or from the stage asviewed from an observer. The reason why the rough/fine motion handle isdisposed in such a way is that a guide for moving the objective lens orthe stage vertically is located at a rear side of the stage and therough/fine motion handle is directly and mechanically coupled to theguide. Usually, an arm for holding the objective lens or the stage isfixed on this guide in a cantilever form.

If the rough/fine motion handle is disposed on the bottom side away fromthe stage as viewed from the front side of the microscope main body, incase where various devices are disposed around the stage to observe thespecimen as seen in, for example, patch clamp method or in case wherethe eye position of the observer is raised depending on microscopesystem, the operability of the rough/fine motion handle is deterioratedconsiderably, which is a problem demanded to be solved.

An example of technology, which has improved the operability of therough/fine motion handle, is a microscope focusing apparatus describedin Jpn. Pat. Appln. KOKAI Publication No. 6-222276. FIG. 1 shows amicroscope provided with this microscope focusing apparatus. Themicroscope shown in FIG. 1 includes a microscope frame 201 comprised ofa horizontal arm portion 201A, a base portion 201B and a verticalportion 201C. A light source 202 is provided on the base portion 201B ofthe microscope frame 201 and the horizontal arm portion 201A has anobjective lens 203, a lens tube 204 and an ocular lens 205.

A fixing base 206 is provided on the vertical portion 201C of themicroscope frame 201 and a moving base 208 is provided on this fixingbase 206 through a guide 207 such that it is movable vertically. A stageholder 209 is supported by this moving base 208 in a cantilever form. Astage 211 for supporting a specimen 210 is provided on this stage holder209 and a condenser lens 212 is provided below it.

An operation handle 213 for moving the stage 211 vertically is supportedrotatably on the base portion 201B, for example, of the microscope frame201. This operation handle 213 has a transmission mechanism of thefollowing structure. The operation handle 213 is connected to alongitudinal base 216 through a pinion gear 214 and a horizontal rackgear 215. This longitudinal base 216 is placed on a fixing plate 218through a guide 217. A horizontal rack 219 is provided on thelongitudinal base 216, with which an idler 220 meshes. This idler 220 isprovided on the moving base 208 and meshes with a vertical rack 221.

Therefore, if the operation handle 213 is operated, a rotation of thisoperation handle 213 is transformed to a motion in the back and forthdirection of the longitudinal base 216 through the pinion 214 and thehorizontal rack 215, and the motion of this longitudinal base 216 istransformed to a vertical motion of the vertical rack 221 through thehorizontal rack 219 and the idler 220. Because the moving base 208 ismoved vertically for the reason, the stage 211 is moved vertically.

However, because in the above described microscope focusing apparatus,the longitudinal base 216 is connected to the operation handle 213through the pinion 214 and the horizontal rack 215 and the horizontalrack 219 and the idler 220 mesh with this longitudinal base 216 whileconnected to the moving base 208 through the vertical rack 221, thestructure of that transmission mechanism is complicated. Consequently,because there are a number of mechanical connecting portions, there is afear that looseness may occur thereby transmission accuracy being notsufficient. Further, this transmission mechanism takes much time andlabor for assembly and adjustment and induces an increased cost.

Further, an objective lens switching apparatus, in which one of pluralobjective lenses 305 is switched selectively onto the observationoptical axis as shown in FIGS. 2 to 7 has been already known.

In a transmission illumination type optical microscope shown in FIG. 2,a revolver 306 holding plural objective lenses 305 as well as an ocularlens-barrel 304 are mounted on an end of the objective arm 303 which isarranged substantially in parallel to the stage 302 of the microscopemain body 301. By rotating this revolver 306, one objective lens isswitched selectively from plural objective lenses 305 onto theobservation optical axis.

The revolver 306 shown in FIG. 2 comprises a revolver main body 306Ashown in FIG. 3 and a turning ring 306B. Plural objective lenses 305 areheld by the turning ring 306B along the circumference of the turningring 306B. A pressing ring 307 is inserted on the side of the turningring 306B between a peripheral portion of the revolver main body 306Aand the turning ring 306B. This pressing ring 307 is fit to an outeredge portion of the revolver main body 306A through balls 308. Further,a ball 309 is held at the rotation center between the revolver main body306A and the turning ring 306B and this ball 309 is pressed at apredetermined force by a pressing screw 310 driven from a rear side ofthe revolver main body 306A. Thus, the turning ring 306B is rotatedsmoothly without any swivel with respect to the revolver main body 306Avia the balls 308, 309.

As shown in FIG. 4, the proximal end of a click spring 311 having aclick ball 312 at a front end thereof is fixed on the revolver main body306A. On the other hand, a click groove 313 is formed in the peripheryportion of the turning ring 306B corresponding to a mounting position ofthe objective lens 305. If the turning ring 306B is rotated so that theobjective lens 305 comes near the optical axis, the click ball 312located at the front end of the click spring 311 drops into the clickgroove 313. As a result, the turning ring 306B is fixed without anyswivel by the pressing force of the click spring 311, so that theobjective lens 305 is positioned on the optical axis.

Recently, a manipulator has been combined with the optical microscope inorder to not only observe a cell but also carry out various kinds ofcell operations such as gripping, piercing, injection and cutting.

FIG. 5 shows schematically the microscope system using such amanipulator. As shown in FIG. 5, an objective lens 318 and a manipulator319, held by the revolver 317, are disposed such that they are adjacenta specimen 316 placed on the stage 315 of the microscope main body 314.This microscope system enables not only to operate the manipulator 319to the specimen 316 but also observe a specimen image through theobjective lens 318. In this system, a controller 320 is connected to themanipulator 319 and rotations of dials 321A, 321B provided on thiscontroller 320 are transformed to fine motion of the manipulator 319.Therefore, the manipulator 319 can be operated finely.

In case of changing the observation magnification of the specimen imagein such a specimen observation, the revolver 317 is rotated so as toswitch the objective lens 318. If it is intended to rotate the revolver317 without any treatment upon this switching, there is generated such aproblem that the manipulator becomes an obstacle, thereby disabling therevolver from being rotated or the objective lens 318 comes into contactwith part of the manipulator 319 during the rotation of the revolver317, so that a front end of the manipulator 319 deflects.

In the positioning mechanism shown in FIG. 4, at an engagement time whenthe click ball 312 drops into the click groove 313 in order to obtain arestoration force for positioning, a pressing force is applied from theclick spring 311 to the click groove 313 in the turning ring 306B.Therefore, a relatively large impact occurs when the click ball 312drops into the click groove 313 and the front end of the manipulator 319is vibrated by this impact, so that the manipulator may be slipped outof a cell being handled.

From such a background, an objective lens replacing apparatus disclosedin Jpn. Pat. Appln. KOKAI Publication No. 6-40910 has been proposedconventionally.

In this apparatus, as shown in FIGS. 6 and 7, two objective lenses OB1,OB2 are installed on a lens switching member 331 movably in a circularshape along the direction of the arrangement. This lens switching member331 is supported rotatably on a fixing member 332 with a ball 333 andball receivers 334, 335. A positioning shaft 336 including multiplethread screw formed therein is driven into a screw hole formed in a sideface of the lens switching member 331. This positioning shaft 336 isdriven by operating the lever 337, so that a positioning ball 338Bprovided on a side face of the fixing member 332 is fit to a conicalconcave portion at a front end of the positioning shaft 336 so as toposition the objective lens OB1. When replacing the objective lens, thedriving of the positioning shaft 336 is loosened by operating the lever337 to release the holding of the lens switching member 331 to thefixing member 332 with the positioning ball 338B. After that, the lensswitching member 331 is rotated with the knob 339 so as to switch theobjective lens OB1 to the objective lens OB2 and then, the positioningshaft 336 is driven again by operating the lever 337 to hold thepositioning ball 338A. As a result, the objective lens OB2 ispositioned.

Because the mechanism shown in FIG. 7 allows the objective lenses OB1,OB2 to move in a circular shape along the direction of the arrangement,an action upon the replacement of the objective lens and a spacenecessary for the replacement operation can be reduced, thereby makingit possible to prevent the objective lenses OB1, OB2 from interferingwith the manipulator and the like around the specimen. Further, thepositioning of the lens switching member 331 is carried out not by usingelasticity of a spring but by driving the positioning shaft 336, whilerelease of the positioning can be carried out by only loosening thedriving of the positioning shaft 336 without linkage with the rotationof the lens switching member 331. Thus, generation of vibration whichmay occur when moving the lens switching member 331 to replace theobjective lens can be minimized to a possible extent.

The mechanism disclosed in the aforementioned Jpn. UM Appln. KOKAIPublication No. 6-40910 has such a problem that it is incapable ofcarrying out an accurate position setting due to a slight gap providedto drive the positioning shaft 336 although such an objective lensswitching mechanism is demanded to execute a position setting in micronorder. Then, although it can be considered to provide with a precisiondriving mechanism capable of eliminating such a gap, provision of a highprecision driving mechanism enlarges the entire size of the positioningmechanism and increases the price of the apparatus.

Further, because upon the replacement of the objective lens, first, thedriving of the positioning shaft 336 is loosened with the lever 337, thelens switching member 331 is rotated with a knob 339 to switch theobjective lens and finally, the positioning shaft 336 is driven with thelever 337, it comes that the lever 337 and the knob 339 need to beoperated at such two positions alternately, thereby leading tocomplicatedness in operation for objective lens replacement.

BRIEF SUMMARY OF THE INVENTION

An object of the present invention is to provide a focusing apparatus ofa microscope capable of improving the operability with a simplestructure.

Another object of the present invention is to provide an objective lensswitching apparatus capable of not only obtaining a high precisionposition reproducibility but also carrying out switching of theobjective lens easily.

Still another object of the present invention is to provide a microscopeprovided with an objective lens switching apparatus including a focusingapparatus capable of improving the operability and an objective lensswitching apparatus capable of not only obtaining a high precisionposition reproducibility but also carrying out selection of theobjective lens easily.

To achieve the above objects, according to an aspect of the presentinvention, there is provided a microscope having an observation side,comprising: a frame main body on which an observation optical systemhaving an observation optical axis is fixed; a stage extended from theframe main body toward the observation side for carrying a specimen;first and second objective lenses for observing the specimen on thestage; an objective lens switching apparatus which holds the first andsecond objective lenses and switches selectively the objective lensesonto the observation optical axis, the objective lens switchingapparatus including a fixing member, a rotating member providedrotatably on the fixing member, in which the first and second objectivelenses are arranged in a circular shape and with a rotation centerprovided on the fixing member, the objective lenses are rotated alongthe direction of the arrangement around the rotation center so as to beselectively positioned on the observation optical axis, a firstrestricting member for restricting a rotation of the rotating member soas to maintain the first objective lens such that it is positioned onthe observation optical axis; a second restricting member forrestricting a rotation of the rotating member so as to maintain thesecond objective lens such that it is positioned on the observationoptical axis; and an applying means for when the rotating memberprovided with the first and second objective lenses is rotated as arotating body, applying a rotation force in an inverse direction largerthan a rotation force generated in the rotation body to the rotatingmember depending on a rotation angle of the rotating member; a focusingmechanism for focusing one of the objective lenses on the specimen onthe stage by moving one of the objective lens switching mechanism andthe stage, the focusing mechanism including, a rough/fine motionfocusing mechanism provided on the frame main body on an opposite sideto the observation side with respect to the optical axis for movingselectively one of the objective lens and the stage in rough/fine motionand provided with a first rough motion handle for moving the rough/finemotion focusing mechanism in rough motion and a first fine motion handlefor moving in fine motion; and a rough/fine motion focusing operationportion provided on the frame main body on the observation side withrespect to the optical axis for moving selectively one of the objectivelens switching mechanism and the stage in linkage with the rough/finemotion focusing mechanism, in rough/fine motion and provided with asecond rough motion handle for moving the one in rough motion relativeto the rough/fine motion focusing mechanism and a second fine motionhandle for moving in fine motion.

According to another aspect of the present invention, there is provideda microscope having an observation optical axis comprising: a frame mainbody having a base portion; an objective lens switching mechanism forswitching two objective lenses by rotating back and forth relative tothe observation optical axis; a stage for carrying a specimen; an ocularlens for observing a specimen image obtained with the objective lens; arough/fine motion focusing mechanism disposed backward of the stage formoving the objective lens switching mechanism in the direction of theobservation optical axis in rough motion or fine motion; a first roughmotion handle and a first fine motion handle provided near therough/fine motion focusing mechanism for operating the rough/fine motionfocusing mechanism; a rough/fine motion focusing operation portionincluding a second rough motion handle and a second fine motion handleprovided near a front end of the base portion for operating therough/fine motion focusing mechanism; a linkage mechanism for linkingthe rough/fine motion focusing mechanism with the rough/fine motionfocusing operation portion; and an operation lever for operating theobjective lens switching mechanism, the rough/fine motion focusingoperation portion and the operation lever being disposed on the side ofthe ocular lens relative to the observation optical axis.

Additional objects and advantages of the invention will be set forth inthe description which follows, and in part will be obvious from thedescription, or may be learned by practice of the invention. The objectsand advantages of the invention may be realized and obtained by means ofthe instrumentalities and combinations particularly pointed outhereinafter.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING

The accompanying drawings, which are incorporated in and constitute apart of the specification, illustrate presently preferred embodiment ofthe invention, and together with the general description given above andthe detailed description of the preferred embodiments given below, serveto explain the principles of the invention.

FIG. 1 is a partially broken side view showing schematically thestructure of a microscope having a conventional focusing apparatus;

FIG. 2 is a side view showing schematically the structure of amicroscope having a conventional objective lens switching apparatus;

FIG. 3 is a side sectional view showing schematically a revolvermechanism applied to the objective lens switching apparatus shown inFIG. 2;

FIG. 4 is a partially broken perspective view showing schematically apositioning mechanism provided in the revolver mechanism shown in FIG.3;

FIG. 5 is a front view showing schematically an optical microscopesystem in which a conventional manipulator is combined;

FIG. 6 is a side view showing schematically other structure of aconventional objective lens switching apparatus;

FIG. 7 is a sectional view schematically the structure of the objectivelens switching mechanism for explaining the structure of the objectivelens switching apparatus shown in FIG. 6;

FIG. 8 is a side view showing schematically a microscope having thefocusing apparatus and the objective lens switching apparatus accordingto the embodiment of the present invention;

FIG. 9 is a front view showing schematically the microscope shown inFIG. 8;

FIG. 10 is a partially broken plan view showing schematically thestructure of the focusing apparatus of the microscope shown in FIG. 8;

FIG. 11 is a partially broken sectional view showing schematically thestructure of a rough movement shaft in the focusing apparatus of themicroscope shown in FIGS. 8 to 10;

FIG. 12 is a sectional view showing schematically the structure of atoothed pulley and a timing belt in the focusing apparatus of themicroscope shown in FIGS. 8 to 10;

FIG. 13 is a partially broken front view showing the structure of anobjective lens switching apparatus in the microscope shown in FIG. 8;

FIG. 14 is a side view showing schematically the structure of theobjective lens switching apparatus in the microscope shown in FIG. 13;

FIG. 15 is a side view showing schematically the structure of theobjective lens switching apparatus in case where an objective lens inthe objective lens switching apparatus shown in FIG. 13 is switched;

FIG. 16 is a partially broken plan view showing schematically thestructure of the objective lens switching apparatus shown in FIG. 13;

FIG. 17 is a partially broken side view showing schematically otherstructure of the objective lens switching apparatus shown in FIG. 13;

FIG. 18 is a partially broken sectional view showing schematically thestructure of the objective lens switching apparatus shown in FIG. 17;

FIG. 19 is a schematic side view for explaining the structure of theobjective lens switching apparatus shown in FIGS. 17 and 18;

FIG. 20 is a front view showing schematically still other structure ofthe objective lens switching apparatus in a partially broken state inthe microscope shown in FIG. 8;

FIG. 21 is a side view showing schematically the structure of theobjective lens switching apparatus in the microscope shown in FIG. 20;

FIG. 22 is a side view showing schematically still other structure ofthe objective lens switching apparatus in a partially broken state inthe microscope shown in FIG. 8; and

FIG. 23 is a side view showing schematically still other structure ofthe objective lens switching apparatus in a partially broken state inthe microscope shown in FIG. 8.

DETAILED DESCRIPTION OF THE INVENTION

Hereinafter, the embodiments of the microscope of the present inventionwill be described with reference to the accompanying drawings.

FIGS. 8 and 9 are a side view and a front view showing schematically amicroscope having the focusing apparatus according to an embodiment ofthe present invention. FIG. 10 is a sectional view showing schematicallythe structure of a base portion viewed from top of the microscope shownin FIGS. 8 and 9.

A microscope frame 30 is formed in the shape of a letter Y and comprisedof a base portion 31 and a vertical portion 32. A horizontal arm portion33 for observation by light projection is installed on this verticalportion 32. This horizontal arm portion 33 for observation by lightprojection contains a downward illuminating light source 34A, andoptical devices such as an ocular lens 35, various kinds of filters andbeam splitter. A transmission illumination light source 34B is providedon a back of the vertical portion 32.

As shown in FIG. 8, a fixing base 36A is screwed on a front side of thebase portion 31 of the microscope frame 30. Two legs 36, 36 are erectedfrom this fixing base 36A and a stage 37 is fixed with these legs 36,36. The vertical portion 32 of the stage 37 is fixed to the base portion31 through a supporting base 38. A condenser lens 39 is supported by thesupporting base 38 below the stage 37. This stage 37 can include a dishcontaining cell and a manipulator (not shown) can be installed forhandling the cell.

A movable base 40 is provided movably upward and downward on thevertical portion 32 of the microscope frame 30. As shown in FIG. 10, themovable base 40 is supported freely movably by a guide body 41. Amovable arm 42 is supported in the cantilever form by the movable base40. This movable arm 42 includes objective lens switching mechanism 44having two objective lenses 43A, 43B, one of which having a desiredmagnification can be used, the objective lens switching mechanism beingdetachable.

A rough/fine motion focusing mechanism, which moves the movable base 40in rough movement or in fine movement upward or downward, is providedbackward of the base portion 31 of the microscope frame 30, that is, ona deeper side than the stage 37 as views from an observer. Thisrough/fine motion focusing mechanism is provided on an opposite side tothe observer with respect to an optical axis of the observation opticalsystem of the microscope, that is, on a rear side of the microscope. Asshown in FIG. 10, this rough/fine motion focusing mechanism includes arough movement shaft 45 and a fine movement shaft 46, providedcoaxially. This rough movement shaft 45 is formed in a hollow structureand the fine movement shaft 46 is inserted into the hollow roughmovement shaft 45. A rough movement handle 47 and a fine movement handle48 are provided on an end portion on the right side in FIG. 10, of eachof the rough movement shaft 45 and the fine movement shaft 46. The roughmovement handle 47 is connected to the rough movement shaft 45 so that arotation force of the rough movement handle 47 is transmitted to therough movement shaft 45 so as to rotate the rough movement shaft 45. Thefine movement handle 48 is connected to the fine movement shaft 46 andfurther connected to the rough movement shaft 45 through a reductiongear (not shown). A toothed pulley 49 is mounted on the other end of therough movement shaft 45 and a fine movement pulley 50, in which aV-shaped groove is formed, is installed on the other end of the finemovement shaft 46.

FIG. 11 shows a section of the central portion of the rough movementshaft 45. A pinion portion 51 is formed in the central portion of thisrough movement shaft 45. This pinion portion 51 has a diameter largerthan an outside diameter of the rough movement shaft 45 and has a toothportion on its outer circumference. This pinion portion 51 meshes with arack 52 fixed on the movable base 40. Meanwhile, the rough movementshaft 45 is supported by a bearing 53 fixed on the base portion 31.

Therefore, if the rough movement handle 47 is rotated, this rotation istransmitted to the rough movement shaft 45 so as to be transformed to avertical motion through the pinion portion 51 and the rack 52. If thisrack 52 is moved up or down, the movable arm 42, on which an objectivelens 43 supported by the movable base 40 is mounted, is moved in roughmovement vertically.

If the fine movement handle 48 is rotated, this rotation is transmittedto the rough movement shaft 45 through a reduction gear with reductionof the rotation speed and transformed to a vertical movement through thepinion portion 51 and the rack 52. When this rack 52 is moved up/down,the movable arm 42, on which the objective lens 43 supported by themovable base 40 is mounted, is moved in fine motion vertically.

On the other hand, the rough/fine motion focusing operation portion formoving the objective lens 43 in rough motion or fine motion is providedon a front portion including a front end of the stage 37. That is, thisrough/fine motion focusing operation portion is provided on a front sidewhich is the side of an observer with respect to the optical axis of theobservation optical system of this microscope. In this rough/fine motionfocusing operation portion, as shown in FIG. 9, a substantiallycylindrical operation portion main body 54A is screwed to the fixingbase 36A fixed at a front end of the base portion 31 of a microscopeframe. This operation portion main body 54A is formed in a hollowstructure as shown in FIG. 10 and a sleeve-like bearing 60, a hollowrough motion shaft 54 and a fine motion shaft 55 are inserted coaxially.A rough motion handle 56 and a fine motion handle 57 are mounted on anend of each of the rough motion shaft 54 and the fine motion shaft 55,for example, on an end on the right side in FIG. 10. Meanwhile, therough motion handle 56 and the fine motion handle 57 are screwed to therough motion shaft 54 and the fine motion shaft 55 respectively.

The rough motion handle 56 is connected to the rough motion shaft 54, sothat a rotation force of the rough motion handle 56 is transmitted tothe rough motion shaft 54 so as to rotate the rough motion shaft 54. Thefine motion handle 57 is connected to the fine motion shaft 55, so thata rotation force of the fine motion handle 57 is transmitted to the finemotion shaft 55 so as to rotate the fine motion shaft 55.

A toothed pulley 58 is attached to the other end of the fine motionshaft 55 and a fine motion knob 59, in which a V-shaped groove on whosecircumferential face a round belt 62 is to be applied is formed, actingas a pulley at the same time, is mounted on the other end of the finemotion shaft 55. Meanwhile, the rough motion shaft 54 is supported bythe bearing 60.

A linkage mechanism is provided between this rough/fine motion focusingoperation portion and the aforementioned rough/fine motion focusingmechanism. A toothed timing belt 61 as shown in FIG. 12 is appliedbetween the toothed pulley 58 and the toothed pulley 49. The round belt62 is applied between a pulley portion of the fine motion pulley 50,that is, the V-shaped groove and a pulley portion in the fine motionknob 59, that is, the V-shaped groove, so that the fine motion pulley 50is connected to the fine motion knob 59. Therefore, the rough/finemotion focusing mechanism and the rough/fine motion focusing operationportion are linked with each other through the toothed timing belt 61,the round belt 62, the fine motion pulley 50, the fine motion knob 59which serves as a pulley at the same time, and the toothed pulleys 49,58.

A stopper handle 63 is provided on an inner side of the rough motionhandle 56 such that it is freely rotatable. Rotating this stopper handle63 in one direction prevents the objective lens 43 from moving downwardso as to reduce a distance between the objective lens 43 and the stage37 further and permits moving thereof upward. That is, when theobjective lens 43 and the stage 37 reach a predetermined gap, therotations of the rough motion handle 56 and the fine motion handle 57which allow the objective lens 43 to be moved downward are locked.

Therefore, if the stopper handle 63 is rotated in one direction when theobjective lens 43 is positioned at a desired position such as justfocusing point by rotating the rough motion handle 56 and the finemotion handle 57, the downward motion of the objective lens 43 is lockedat that position, so that the objective lens 43 is allowed to be movedonly within a range upward from that position. Meanwhile, if the stopperhandle 63 is rotated in the other direction, the downward motion of theobjective lens 43 is unlocked.

In this way, the objective lens 43 is protected from falling down withrespect to a locked position, for example, a focusing position. Afterthe objective lens 43 is moved upward, the objective lens 43 isdescended so as to attain refocusing so that the objective lens 43 isreturned to the focusing position.

Next, the operation of the focusing apparatus having the structure shownin FIGS. 8 to 12 will be described.

When the observer places a specimen on the stage 37 and observes it, herotates the rough motion handle 56 or the fine motion handle 57 providedon the front side of the microscope.

If the rough motion handle 56 on the front side is rotated, thisrotation is transmitted to the timing belt 61 from the rough motionshaft 54 through the toothed pulley 58 and further transmitted from thetoothed pulley 49 located deeper than the stage 37 to the rough motionshaft 45. Then, if this rough movement shaft 45 is rotated, thisrotation is transformed to a vertical motion on the movable base 40 fromthe pinion portion 51 through the rack 52. If this rack 52 is movedup/down, the movable arm 42, on which the objective lens supported bythe movable base 40 is mounted, is moved up/down in rough motion.

If the fine motion handle 57 on the front side is rotated, this rotationis transmitted from the fine motion shaft 55 to the round belt 62through the fine motion knob 59 and further transmitted to the finemovement shaft 46 from the fine movement pulley 50 located deeper thanthe stage 37. Then, if this fine movement shaft 46 is rotated, thisrotation is reduced in speed by a reduction gear and transmitted to therough movement shaft 45, so that the rotation of this rough movementshaft 45 is transformed to a vertical motion from the pinion portion 51through the rack 52. If this rack 52 is moved up/down, the movable arm42, on which the objective lens 43 supported by the movable base 40 ismounted, is moved up/down in fine motion.

A case where the observer rotates the rough motion handle 56 or the finemotion handle 57 is, for example, a case where he sets up a manipulatorand observes a specimen by handling this manipulator or a case wherebecause the specimen is so large, a spacer is located between thevertical portion 32 and the horizontal arm portion 33 so as to raise aneye-point of the ocular lens 35. Because the rough motion handle 56 andthe fine motion handle 57 on the front side are located at a place wherethe observer can reach easily with his hand, in this case, he canoperate the rough motion handle 56 and the fine motion handle 57 whileobserving the specimen.

When the objective lens 43 is replaced during observation of thespecimen or the specimen is replaced or some processing is carried outon the specimen, the stopper handle 63 on the front side is rotated inone direction, so that the rotation of this stop handle 63 in onedirection locks a downward movement of the objective lens 43.

In replacement of the objective lens 43, replacement of the specimen orsome processing on the specimen, usually, the rough motion handle 56 andthe fine motion handle 57 are operated so as to move the objective lens43 upward. If during such an operation, the objective lens is locked,even if the rough motion handle 56 and the fine motion handle 57 areoperated erroneously, the objective lens 43 is not dropped from thelocked position so that the safety of the specimen is secured.

In case of focusing again to the specimen after the replacement of theobjective lens 43, the replacement of the specimen or some processing onthe specimen, the objective lens 43 is descended to the locking positionand the locking is released with the stopper handle 63, therebyfacilitating refocusing.

The procedure for the observer to take for observing the specimen is asfollows. Assume that as the objective lens 43, two objective lenses,namely, a low magnification (for example, 10-power) and a highmagnification (for example, 40-power) are mounted on the objective lensswitching apparatus 44.

-   (1) The observer releases the lock by operating the stopper handle    63 from the beginning.-   (2) Next, the observer operates an operation handle 56, moving the    objective lens 43 upward to secure a gap between the stage 37 and    the objective lens 43.-   (3) After that, a dish 70 containing a living specimen of an    observation object is placed on the stage 37.-   (4) An operation lever 117 for switching the objective lens is    operated to switch from the high magnification lens to the low    magnification lens.-   (5) The rough motion handle 56 and the fine motion handle 57 (or the    fine motion knob 59) is operated to make focusing on the specimen.-   (6) A portion desired to be observed of the specimen is aligned with    the center of field of view.-   (7) The rough motion handle 56 is operated to move the objective    lens 43 upward.-   (8) The operation lever 117 for switching the objective lens 43 is    operated to switch to the high magnification objective lens 43.-   (9) The rough motion handle 56 and the fine motion handle 57 (or    fine motion knob 59) are operated to make focusing on the specimen.-   (10) The stopper handle 63 is operated to make locking.

Upon replacement of the specimen or objective lens 43 after such seriesoperation, the objective lens 43 is retreated upward with the locking bythe stopper handle 63. In this operation, for the microscope 43, therough motion handle 56 for moving the objective lens 43 up/down, thefine motion handle 57, the stopper handle 63 and the operation lever 117for switching the objective lens are operated. Because these componentsare disposed forward of the microscope 43 (forward of the observationoptical axis), their operations are easy.

According to the above-described embodiment, the rough motion shaft 54and the fine motion shaft 55 are provided coaxially on the front sideincluding a front end portion of the stage 37 and the rough motionhandle 56 and the fine motion handle 57 are attached to each end of therough motion shaft 54 and the rough motion shaft 55. Further, theserough motion shaft 54 and fine motion shaft 55 are linked with the roughmovement shaft 45 and the fine movement shaft 46 located deeper than thestage 37 through the timing belt 61 and the round belt 62 so as to movethe objective lens 43 in rough motion or fine motion. Thus, in casewhere the manipulator is set up for the specimen and that specimen isobserved or in case where because the specimen is so large, a spacer isimposed between the vertical portion 32 and the horizontal arm portion33, so that the position (eye position) of the ocular lens 35 is raised,the rough motion handle 56 and the fine motion handle 57 on the frontside can be operated easily, thereby improving the operability duringobservation of the specimen.

The structure of the rough/fine motion focusing operation portioncomprised of the rough motion shaft 54 and the rough motion shaft 55located on the front side, the rough motion handle 56 and the finemotion handle 57 is substantially the same as the structure of therough/fine motion focusing mechanism comprised of the rough movementshaft 45 and the fine movement shaft 46 located deep on the stage 37,the rough movement handle 47 and the fine movement handle 48. Furtherbecause they are linked with each other through the timing belt 61 andthe round belt 62, with such a simple structure, transmission accuracycan be improved with little looseness.

Therefore, the assembly of the rough/fine motion focusing operationportion, the rough/fine motion focusing mechanism and the linkingmechanism is easy and the adjustment thereof is also easy. Additionally,these mechanisms can be added at a cheap cost.

Because the stopper handle 63 is provided on the front side, whenrefocusing is carried out with the downward motion of the objective lens43 locked, for example, when a specimen is observed by handling themanipulator or the specimen is so large that the eye point is raised,the refocusing operation can be carried out easily.

The rough/fine motion operating mechanism of this embodiment can beattached to a microscope having a conventional focusing mechanism after.That is, the fixing base on which the operation portion main body isfixed is installed on a front end of the base portion of the microscopeframe and then, the rough motion handle and the fine motion handle ofthe existing focusing mechanism are replaced with pulleys and thesepulleys are connected to a rough motion pulley and a fine motion pulleyof the operation portion main body with two belts. Consequently, thefocusing operation portion can be situated forward of the observationoptical axis without a large reconstruction by using the existingfocusing mechanism disposed backward of the observation optical axis asit is.

According to this embodiment, the mounting base for use in fixing theoperation portion main body on the base portion of the microscope frameis employed for fixing the legs supporting the stage at the same time.As a result, such a large stage can be held stably and because therough/fine motion focusing operation portion is disposed forward, theoperability of the focusing mechanism can be maintained excellent evenif the stage is enlarged so that it is extended forward.

The focusing mechanism according to the above described embodiment maybe modified as follows.

Although according to the above-described embodiment, the movable arm 42on which the objective lens 43 is to be mounted is moved vertically bythe rough motion handle 56 and the fine motion handle 57 on the frontside, it is permissible to apply such a structure that the stage 37 ismoved vertically to the focusing mechanism. This structure that thestage is moved vertically has been disclosed in U.S. Ser. No. 09/729,592“Drive Mechanism of Focusing Device” (invented by Souji Yamamoto) filedDec. 4, 2000, now U.S. Pat. No. 6,512,632, which is assigned to the sameassignee as this application and all the content of this priorapplication is incorporated in this specification. In this priorapplication, the rough/fine motion focusing mechanism is provided on anopposite side to the front side with respect to the optical axis of themicroscope as described previously. Therefore, if the rough/fine motionfocusing operation portion described with reference to FIGS. 8 to 12 isso constructed to drive the rough/fine motion focusing mechanism throughthe linking mechanism, such a structure that the stage is movedvertically is achieved. Additionally, a stopper mechanism forrestricting the motion of the stage has been also disclosed in thisprior application as shown in FIG. 6. This stopper mechanism isapplicable to a mechanism including the stopper handle 63 shown in FIG.10. A description of the rough/fine motion focusing mechanism for movingthe stage vertically and the stopper mechanism is omitted byincorporating all the content of the aforementioned prior application toUS patent in this specification, for simplification of the descriptionthereof.

Although the respective rough motion handles 47, 56 and the respectivefine motion handles 48, 57 are installed on the right side of themicroscope as shown in FIG. 10, they may be installed on the left sideor both sides.

Next, the objective lens switching mechanism 44 of the microscope shownin FIG. 8 will be described.

The objective lens switching mechanism 44 shown in FIGS. 13 to 16 isheld by the movable arm 42. FIG. 13 is a partially broken front viewshowing schematically the structure of the objective lens switchingmechanism 44 and part thereof indicates a sectional view around therotation shaft. FIGS. 14 and 15 are side views of the objective lensswitching mechanism 44 shown in FIG. 11 for explaining an operation ofthe objective lens switching mechanism 44.

As shown in FIGS. 8 and 9, the movable arm 42 is provided with a femaledovetail (not shown) for fixing the objective lens switching mechanism44. The objective lens switching mechanism 44 includes a fixing member111 shown in FIG. 13 and this fixing member 111 has a male dovetailwhich is joined to the female dovetail on the side of the movable arm42. Further, a rotating member 113 is supported rotatably through arotation shaft 115 disposed in a direction perpendicular to the opticalaxis Z0 of the microscope. This rotating shaft 115 is provided on thefixing member 111 via a bearing 114, so that the rotating member 113 isheld rotatably without any swing.

The objective lens 43A, 43B are disposed circularly on the rotatingmember 113 and when this rotating member 113 is rotated, these objectivelenses 43A, 43B are rotated along the direction of their disposal. Thisrotating member 113 includes a mounting portion 116 on which theobjective lenses 43A, 43B are to be screwed, for example, screw hole.The mounting portion 116 is pressed by a pressing member 124 comprisedof a cylindrical convex portion 124A and a coil spring 124B through asingle point and by driving screw members 125 from two directionsagainst this pressing point as shown in FIG. 16, the position of theobjective lens can be adjusted. That is, by adjusting a driving amountof the screw member 125, axial deviation of the rotating member 113including the axial deviation of the objective lenses 43A, 43B isadjusted so that a deflection of an observation position when theobjective lenses 43A, 43B are switched is eliminated.

Restricting members 121A, 121B for restricting the rotation of therotating member 113 are provided on an end portion in the back and forthdirection of the fixing member 111. The rotating member 113 has contactportions 122A, 122B which contact the restricting members 121A, 121B dueto the rotation thereof. In this case, a protrusion amount of each ofthe restricting members 121A, 121B is adjusted so that the objectivelenses 43A, 43B and the optical axis Z0 are positioned accurately whenthe objective lenses 43A, 43B are switched, and with this condition,they are fixed with screws or adhesive agent.

The rotating member 113 is provided with two weights 123, 123 as anurging means. These weights 123, 123 are provided to hold the posture ofthe rotating member 113 when the contact portions 122A, 122B of therotating member 113 make contact with the restricting members 121A, 121Bin order to switch the objective lenses 43A, 43B. As shown in FIG. 14,the weight 123 is rotated around the same rotation center O as therotating member 113 and disposed in an opposite direction to theobjective lenses 43A, 43B along an axis Zb passing the intermediate ofan angle in the rotation direction between the objective lenses 43A and43B. The weight 123 has an axis Zb which is inclined at 45° with respectto the optical axis Z0 so that it does not obstruct an apparatus forcell operation such as the manipulator and does not interfere with thefixing member 111 when the rotating member 113 is rotated. That is, theweight 123 is constituted of a mounting portion 123A to the rotatingmember 113 and a weight main body 123B having the axis Zb, and has agravity center at a position X on the axis Zb apart from the rotationcenter O of the rotating member 113.

As shown in FIG. 13, the fixing member 111 has fixing side indexes 118,119 and the rotating member 113 has a diamond shaped rotating side index120. The fixing side indexes 118, 119 and the rotating side index 120are disposed along the rotation direction of the rotating member 113. Atboth ends of the rotation range of the rotating member 113, it isnotified an operator that the rotating side index 120 approaches thefixing side index 118 or 119 along the rotation direction so that therotating member 113 approaches the restricting members 121A, 121B.

When the objective lens 43A is switched onto the optical axis Z0 byrotating the rotating member 113 shown in FIG. 13 forward, it can benotified the operator that when the contact portion 122A of the rotatingmember 113 approaches the restricting member 121A, a front end portionof the rotating side index 120 approaches a vertex of the triangularfixing side index 118. Further, if the rotating member is rotatedbackward so as to switch the objective lens 43B onto the optical axisZ0, it can be notified the operator by a fact that the front end portionof the rotating side index approaches the vertex of the triangularfixing side index 119 when the contact portion 122B of the rotatingmember 113 approaches the restricting member 121B as shown in FIG. 15.If the rotating side index 120 and the fixing side indexes 118, 119 arepositioned at the height of the eye line of the operator at the frontface of the microscope main body, it is possible to make the operatorrecognize switching condition of the objective lenses 43A, 43Baccurately.

The rotating member 113 is provided with the operation lever 117 foroperating its rotation and the rotating member 113 is rotated by thisoperation lever 117 when switching the objective lenses 43A, 43B.

Next, an operation of the objective lens switching mechanism 44 havingsuch a structure will be described.

Now, in a condition that as shown in FIG. 14, the objective lens 43A isswitched onto the optical axis Z0, the objective lenses 43A, 43B and therotating member 113 correspond to a rotary body. If the gravity centerof this rotary body is assumed to be Y, rotary moment My is indicated bya product of mass W1 of the rotary body and a horizontal distance Dabetween the rotation center O of the rotating member 113 and Y, that is,My=W1·Da. On the contrary, if the gravity center of the weight 123 isassumed to be X (opposite side to the gravity center Y with respect tothe rotation center O of the rotating member 113), the rotary moment Mxis indicated by a product of mass W2 of the weight 123 and a horizontaldistance Db between the rotation center of the rotating member 113 andX, that is, Mx=W2·Db. If the rotary moments My, Mx are set up so thatMx>My by using the weight 123 having a sufficiently large mass W2, thisis larger than the rotation force by the rotary body comprised of therotating member 113 and the objective lenses 43A, 43B, so that if arotation force in inverse direction is applied depending on the rotationangle of the rotating member 113, a force in a contact direction withthe restricting member 121A acts on the rotating member 113 due to thisrotary moment Mx thereby making it possible to hold the objective lens43A on the optical axis Z0.

If from this condition, the rotating member 113 is rotated with theoperation lever 117 as shown in FIG. 15 so as to switch the objectivelens 43B onto the optical axis Z0, the gravity center of the rotary bodyat this time is moved to Q. Thus, a rotary moment Mq becomes Mq=W1·Daand the gravity center of the weight 123 is moved to P, so that therotary moment Mp becomes Mp=W2B. In this case also, the relationship ofMp>M1 is generated and so a force in a contact direction with therestricting member 121B acts on the rotating member 113, thereby makingit possible to hold the objective lens 43B on the optical axis Z0.

As for the objective lenses 43A, 43B to be installed onto the rotatingmember 113, sometimes, a low magnification one having a small mass and ahigh magnification one having a large mass are installed mixedly. Thus,the gravity center of the rotary body may be deflected to the side ofthe high magnification one having such a large mass. However, if evenwhen an objective lens having a maximum weight is mounted as the weight123, such a lens having a large mass W2 is prepared to be able to movethe rotating member 113 to the side of the restricting members 121A,121B, even if weight balance is destroyed on the side of the rotatingmember 113, a force capable of moving the rotating member 113 to theside of the restricting members 121A, 121B securely can be applied.Although an operation force intensity when switching the objective lensincreases with SIN function, change of force is attained substantiallyproportionally because the rotary angle is substantially 30°.

Thus, the objective lenses 43A, 43B can be switched onto the opticalaxis Z0 by only operating the operation lever 117 according to theoperation force intensity determined by a rotary moment of the weight123. Further, the rotating member 113 is positioned by being made intocontact with the restricting members 121A, 121B. Therefore, as comparedto a conventional positioning mechanism employing a click mechanism,accompanied by a sudden change of force intensity for introducing theclick, no sudden change of the force is generated for positioning theobjective lens, so that a smooth switching operation without anyvibration, required in manipulator operation can be assured.

Further, such a switching operation condition can be notified to theoperator by a motion of the rotating side index 120 relative to thefixing side indexes 118, 119. Thus, by carrying out a careful operationjust before the rotating member 113 strikes the restricting members121A, 121B, a further accurate vibration free condition can be realized.

Further, because the rotating member 113 is positioned by making it incontact with the restricting members 121A, 121B, positionreproducibility of micron order can be achieved, which is demanded inobjective lens switching operation.

Because the switching of the objective lenses 43A, 43B can be carriedout by only operating the operation lever 117, the switching operationcan be executed easily.

A second embodiment of the lens switching mechanism 44 of the presentinvention will be described with reference to FIGS. 17 to 19.

FIG. 17 is a front view of the objective lens switching mechanism 44 andpart thereof indicates a sectional view around the rotation shaft. FIG.18 is a side view of the same objective lens switching mechanism. InFIGS. 17 to 18, like reference numerals are attached to the samecomponents as FIGS. 13 to 15 and a description thereof is omitted.

A cover 130 is attached to the side face of the fixing member 111 and afixing portion supporting column 131 is provided as a spring fulcrum onan inner face of this cover 130. Further, a rotation side supportingcolumn 132 is provided as a spring fulcrum on the side face of therotating member 113 inside the cover 130. A tension spring 133 isprovided between the fixing portion supporting column 131 and therotation side supporting fulcrum 132.

These fixing portion supporting column 131 and rotation side supportingcolumn 132 are disposed such that with the rotating member 113 locatedin the center of a rotation range, they sandwich the rotation shaft 115supporting the rotating member 113 rotatably, in other words, theysandwich a rotation center O of the rotating member 113. Assuming that,as shown in FIG. 19, the radius of a trace drawn by the rotation sidesupporting column 132 when the rotating member 113 is rotated withrespect to the rotation center O of the rotating member 113, is R1 andthe radius of a trace drawn by the rotation side supporting column 132relative to the fixing portion supporting column 131 when the objectivelens 43A (43B) is positioned to the optical axis Z0, is R2 while therelation of R2>R1 is maintained, these R1, R2 are determined tointersect each other at positions where the objective lenses 43A, 43Bare positioned on the optical axis Z0, that is, on both end positions A,B in the rotation range of the rotating member 113.

Under such a condition, a rotary moment of the tension spring 133 isgiven as a product of component of force in the rotation direction ofthe rotating member 113 and the radius R1 and this rotary moment isinverted in its application direction across the center portion of therotation range of the rotating member 113. If the rotary moment at thistime is set up to be sufficiently larger than the rotary moment by therotating member 113, that is, in this case also, a rotation force largerthan that caused by the rotating body comprised of the rotating member113 and the objective lenses 43A, 43B in an opposite direction isallowed to act depending on the rotation angle of the rotating member113, a force for bringing rotating member 113 into contact with therestricting members 121A, 121B is applied by the rotary moment of thetension spring 133, so as to hold the objective lenses 43A, 43B on theoptical axis Z0.

Thus, if the operation lever 117 is operated with an operation forceintensity determined by the rotary moment by the tension spring 133, theswitching and positioning of the objective lens are enabled as describedabove. Therefore, the switching operation without any vibration demandedin manipulator operation can be obtained easily.

Further, because as for the operation force at this time, as it goes toboth ends of the operation range, change of the force relative to therotation angle decreases, the operation can recognize a substantialoperation position and therefore, by carrying out careful operationdepending on an operation position, a further higher precision vibrationfree state can be realized.

Further, because the tension spring 133 is incorporated inside the cover130, so that a protrusion of the apparatus to the surrounding thereofcan be reduced, a large manipulator installation space can be assuredthereby making it possible to smooth the operation of the manipulator.

Further, because reduction in size and weight of the apparatus can beachieved, the apparatus can be handled easily when replacing theobjective lens. Because the rotation force is obtained from the tensionspring 133, such a restriction in the mounting direction to themicroscope main body is eliminated unlike a case where theaforementioned weight is employed, and consequently, this apparatus canbe applied to, for example, an inverted type microscope.

Next, a third embodiment of the lens switching mechanism 44 of thepresent invention will be described with reference to FIGS. 20 and 21.

FIG. 20 is a front view of the objective lens switching mechanism 44 andpart thereof indicates a sectional view around the rotation shaft. FIG.21 is a side view of the objective lens switching mechanism 44. In FIGS.19 and 20, like reference numerals are attached to the same componentsas FIGS. 13 to 15 and a description thereof is omitted.

The rotating member 113 contains a female screw 126 directed to the sideface of the fixing member 111 and a rounded corner screw 127, which hasa semispherical head, is driven into an end of this female screw 126. Afriction member 128 of fan shaped resin is bonded to the side face ofthe fixing member 111. This friction member 128 is extended on the sideface of the fixing member 111 so that with a rotation of the rotatingmember 113, the semispherical rounded corner screw 127 moves on thefriction member 128 while keeping in contact therewith. On both endpositions of the extension of this friction member 128, the roundedcorner screw 127 leaves the friction member 128 and comes into a directcontact with the side face of the fixing member 111. That is, on bothend positions of the rotation range of the rotating member 113, namelyjust before the contact portions 122A, 122B come into contact with therestricting members 121A, 121B, the rounded corner screw 127 leaves thefriction member 128 and comes into direct contact with the side face ofthe fixing member 111. In an intermediate range before the contactportions 122A, 122B come into contact with the restricting members 121A,121B, the rounded corner screw 127 stays on the friction member 128, sothat a holding force is secured between the both.

In the lens switching mechanism 44 shown in FIGS. 20 and 21, when theobjective lens 43A is positioned to the optical axis Z0 as shown in FIG.20, a rotary moment in the direction trying to bring the restrictingmember 121A into a firm contact with the contact portion 112A, generatedby the weight 123 is larger than a rotary moment generated by weights ofthe objective lens 43B and the rotating member 113 on a front portionhaving this optical axis Zb. Therefore, the restricting member 121A andthe contact portion 112A are kept in a firm contact with each other andthe objective lens 43A on a rear side is positioned such that theoptical axis of the objective lens 43A coincides with the optical axisZ0.

When an observer or an operator switches the objective lens 43A to otherobjective lens 43B, the operation lever 117 is operated so as to rotatethe rotating member 113. After the rotation starts, the restrictingmember 121A leaves the contact portion 112A and then a front end of therounded corner screw 127 touches the friction member 128. If therotating member 113 is rotated further, the front end of the roundedcorner screw 127 rides on the friction member 128 and slides over thefriction member 128 with a large friction. This friction force acts toprevent a rotation of the rotating member 113 and cancels a rotarymoment generated by the weights of the objective lens 43B and therotating member 113 or weight of the weight 123, so that this frictionforce acts to hold the rotating member 113 on the fixing member 111 witha larger force than this rotary moment. Therefore, even if the operatorreleases his hand from the operation lever 117, the rotating member 113and the objective lens 43A are not rotated, but kept at that position.If the operator gives a larger force than a holding force generated byfriction to the operation lever 117, the rotating member 113 is furtherrotated. Because the holding force generated by friction is approximateto a force which the operator can give to the operation lever 117 andthere is an appropriate balance between the both forces, the operatordoes not feel a large burden when operating the lever. Because therounded corner screw 127 is advanced or retreated so as to adjust thepressing force of the front end of the rounded corner screw to thefriction member 128, the holding force generated by that friction forcecan be adjusted.

When the rotating member 113 is rotated by the operator's operating theoperation lever 117 and the objective lens 43B on the front sideapproaches the optical axis Z0, the restricting member 123B approachesthe contact portion 122B, so that just before the restricting member123B comes into a contact with the contact portion 122B, the front endof the rounded corner screw 127 leaves the friction member 128, therebyeliminating the friction force between the both. In this condition, therotary moment of the objective lens 43A and the rotary member 113 islarger than the rotary moment by the weight of the weight 123, so thatan action force for bringing the restricting member 123B into a firmcontact with the contact member 122B is generated and then, therestricting member 123B comes into a firm contact with the contactmember 122B. Thus, the objective lens 43B on the front side ispositioned on the optical axis Z0 at a high precision and kept as it is.

Even if the observer releases the operation lever 117 by mistake duringthe operation, because the objective lens 43A and the rotating member113 are kept to the fixing member 111 by the friction force as describedabove, there is no fear that the objective lens 43A and the rotatingmember 113 may accelerate toward one of combinations of the restrictingmembers 121A, 121B and the contact members 122A, 122B and strike eachother. Further, because the objective lens 43A and the rotating member113 are kept until just before the restricting member 121 and thecontact member 122 strike each other, the operator does not have to takecare of the operation. Thus, any index for notifying that therestricting member 121 and the contact member 122 approach each other isnot necessary. The change in force upon operation is small because thefriction member 128 is made of thin sheet-like resin and further, thefriction force can be adjusted to be slightly larger than the rotarymoment by the weight 123, so that no large impact is generated unlike aconventional click mechanism, thereby preventing generation of vibrationwhich affects inspection by observation and manipulation.

Because the lens switching mechanism has the above described structure,there is no sudden change in force for calling, which is generated bythe click used as a positioning mechanism in the conventional example,thereby eliminating the necessity of taking care of an accuratedistribution of applied force while seeing the index upon the operationand facilitating the switching operation without any vibration demandedin manipulation operation. Further, because the positioning is carriedout with the rotating member in contact with the restricting member,position reproducibility in micron order demanded in the objective lensswitching apparatus can be achieved.

A fourth embodiment of the lens switching mechanism of the presentinvention will be described with reference to FIG. 22.

FIG. 22 is a side sectional view showing schematically the structure ofthe fourth embodiment of the lens switching mechanism 44 of the presentinvention, indicating surrounding around the rotation shaft 115 with apartially broken view. FIG. 22 indicates a state when the objective lens43A on the rear side is positioned on the optical axis Z0 of themicroscope. In FIG. 22, like reference numerals are attached to the samecomponent as FIGS. 13 to 20 and a description thereof is omitted.

The description of the lens switching mechanism of the fourth embodimentis omitted because the structure is substantially the same as describedabove.

In the mechanism shown in FIG. 22, the tension spring 133 described inthe second embodiment is replaced with a weight as an example in whichthe same effect as the weight 123 described in the third embodiment isobtained. Because the effect of the tension spring 133 is the same asthe second embodiment, see the description made with reference to FIG.19.

As described above, the rotary moment by the tension spring 113 isinverted in the application direction across the center of the rotationrange. The rotary moment by the tension spring 113 is a product ofcomponent of force in the rotation direction of the rotating member 113and the radius R1 and the rotary moment by the tension spring 113 isdetermined to be larger than the rotary moment generated by the rotatingbody. That is, such a state that with the rotating member 113 in contactwith the restricting member 121B, the objective lens 43A is positionedon the optical axis Z0 of the microscope is maintained.

In such a mechanism, a pressing member 154 so shaped as if a top face ofa cone is flattened is provided on the inner face of the rotating member113. An inner face of this rotating member 113 is formed on the sametrace face as a circular face on a concentric circle on which therotating member 113 rotates and a fixing member 111 having an outer faceof a circular face on a concentric circle with a slight gap relative tothis face is provided. A belt-like leaf spring 153 is provided on atrace formed by the pressing member 154 when it moves along that outerface. The leaf spring 153 has an arc slightly floating over the outercircular face of the fixing member 111 as shown in FIG. 22 while boththe ends are fixed to the fixing member 111 such that they contact itfirmly. In a state shown in FIG. 22, the pressing member 154 is situatedat a position where the leaf spring 153 is in a firm contact with theouter face of the fixing member 111 in a mild form, while it is not yetin contact with the pressing member 154. With this state, because theforce by the tension spring 133 exceeds the rotary moment by the weightsof the objective lens 43A and the rotating member 113, the restrictingmember 121 is kept in a firm contact with the contact member 122. If theobserver operates the operation lever 117 from this state and therotating member is rotated so as to switch the objective lens 43A to thefront side, the restricting member 121 is separated from the contactmember 122, so that the pressing member 154 comes into a contact withthe leaf spring 153 gradually. Because a friction force is generated bya force of the pressing member 154 for pressing the leaf spring 153 anda repulsive force of the leaf spring 153 which repels that force andthat friction force exceeds a force of the tension spring 133, therotation of the objective lens 43A and the rotating member 113 by thetension spring 133 is extinguished. Therefore, even if the observerreleases his hand from the operation lever 117, the objective lens 43Aand the rotating member 113 are kept at their positions so that they arenot rotated in any direction.

If the observer rotates the objective lens 43A and the rotating member113 further resisting this friction force (a force holding the objectivelens 43A and the rotating member 113), when the objective lens 43A onthe front side approaches a state just before it is positioned on theoptical axis, a force which presses the pressing member 154 against theleaf spring 153 decreases gradually. As a result, when the restrictingmember 121A on an opposite side comes into a contact with the contactmember 122A, the pressing member 154 is completely separated from theleaf spring 153. As for a force on the lever 117, heaviness by thefriction force decreases gradually from such a level that some extent ofheaviness exists due to holding with the friction force andcorrespondingly, a force acting in a direction for bringing therestricting member 121A into a contact with the contact member 122A isgenerated by the tension spring 133. Because this force increasesgradually since just before such a contact, even if the lever 117 is notoperated carefully, there is no fear that vibration or a collision ofthe contact member 122A occurs. During a rotation stroke of the rotatingmember 113, it is permitted to release his hand, so that a special caredoes not have to be taken to the operation.

With the above described structure, as compared to the third embodiment,the size of the apparatus can be reduced and when reducing the frictionforce from just before the contact member 122A during the rotationstroke, the force intensity can be changed further smoothly due to theshape of the leaf spring 153. Further, the friction mechanism can beformed inside, thereby eliminating an influence of dust and dirt fromoutside.

Further, a fifth embodiment of the lens switching mechanism 44 of thepresent invention will be described with reference to FIG. 23.

FIG. 23 is a side sectional view showing schematically the fifthembodiment of the lens switching mechanism of the present invention,indicating the surrounding of the rotation shaft 115 in a partiallybroken view. FIG. 22 indicates a state in which the objective lens 43Ais positioned on the optical axis Z0 of the microscope. In FIG. 23, likereference numerals are attached to the same components as FIGS. 13 to 22and a description thereof is omitted.

According to the fifth embodiment of the lens switching mechanism, therotating member 113 is provided with a female screw hole 161 which isdirected to the rotation center of the rotating member 113 as well asthe objective lens mounting screw hole 116 and a screw 162 is driveninto that hole toward the outer face of the fixing member 111 fromoutside. The inside of the screw 162 contains a cavity and a roundedcorner member 163 made of resin or metal is incorporated in the cavitysuch that it is inserted and slid. A compression spring 164 is includedbetween the bottom of the cavity in the screw 162 and the bottom of therounded corner member 163. The rounded corner member 163 is providedwith a flange portion, which prevents the rounded corner member 163 frombeing slipped and jumped out of the screw 162 by the compression spring164.

In a state shown in FIG. 23, the objective lens 43B on the rear sideremains positioned, so that a force which presses the restricting member121 against the contact member 122 is applied by the tension spring 133.If the observer rotates the rotating member 113 by operating theoperation lever 117, a rounded corner member 163 comes into contact withan outer circular face 165 gradually because the outer circular face 165provided on the fixing member 111 has a shape shown in FIG. 23, so thatthe rounded corner member 163 is pressed by the compression spring 164.Thus, a friction force is generated between the compression spring 164and the outer circular face 165 or the fixing member 111. Because thisfriction force is stronger than a force of the tension spring 133 tryingto rotate the objective lens 43A and the rotating member 113, the fixingmember 111 and the rotating member 113 are held within a rotation strokein which this friction force is exerted sufficiently. Therefore, even ifthe hand is released from the operation lever 117, the objective lens42A and the rotating member 113 can be stopped at that position. As therotating member 113 is rotated further by operating the operation lever117, the rounded corner member 163 begins to leave the outer circularface 165 gradually since just before the restricting member 121A on anopposite side strikes the contact member 122A. When the restrictingmember 121A comes into a firm contact with the contact member 122A, theyare separated completely so that there is no holding force. With thiscondition, the restricting member 121 is pressed against the contactmember 122 by a force of the tension spring 133, so that the objectivelens 43A is positioned on the optical axis.

The outer circular face 165 has a circular face which is concentric withan arc of the inner face of the rotating member 113 except on both endsof the rotation stroke of the rotating member 113. The surface of theouter circular face 165 departs from the rounded corner member 163gradually as the rounded corner member 163 approaches both ends of theouter circular face 165, so that it approaches the rotation center ofthe rotating member 113. Therefore, a change in friction force isgenerated between the outer circular face 165 and the rounded cornermember 163 which advances tracing this face. Because this face changessmoothly, no sudden change of force intensity is generated unlike theclick mechanism or no vibration is generated.

As described above, there is not generated a sudden change in forceintensity when positioning the objective lens, so that switchingoperation without any vibration demanded in the manipulation operationcan be done easily. Further, because the positioning is performed bybringing the rotating member into a contact with the restricting member,position reproducibility in micron order, demanded in the objective lensswitching apparatus can be achieved. Further, the switching operation issimplified because it is carried out only by operating the operationlever. Further, the protrusion of the apparatus to the objective lensswitching apparatus can be reduced so that a wide installation space forthe micro manipulator can be assured. Further, no special care does nothave to be taken in operating the operation lever upon switchingoperation, and even if the hand is released from the lever during theoperation, there is no fear that the objective lens may move naturally.

Further, the configuration of the rotating member is simplified, therebymaking it possible to provide a cheap apparatus. Because elasticity ofthe leaf spring is employed as the friction force, the durability of theapparatus is high. Further, because the system configuration is formedinternally, it is highly resistant to dust, dirt and the like.

Further, because fine adjustment of the friction force is possible andthe mechanism is simple, a cheaper apparatus can be provided. Becausethe entire mechanism can be disposed within a small space, the apparatuscan be reduced to a compact size.

Meanwhile, a following invention is included in the above describedembodiments.

The objective lens switching apparatus of the present inventioncomprises two fixing side indexes provided on the fixing member and arotation side index provided on the rotating member, such that theseindexes are disposed along the rotation direction of the rotating memberand the rotation side index approaches the fixing side indexes on bothends of the rotation range of the rotating member.

Consequently, it can be informed the operator that the rotating memberhas approached the restricting member. Thus, by carrying out carefuloperation since just before the rotating member strikes the restrictingmember, a further high precision vibration free state can be achieved.

Additional advantages and modifications will readily occur to thoseskilled in the art. Therefore, the invention in its broader aspects isnot limited to the specific details and representative embodiments shownand described herein. Accordingly, various modifications may be madewithout departing from the sprit or scope of the general inventiveconcept as defined by the appended claims and their equivalents.

1. A microscope having an observation optical axis, said microscopecomprising: a frame main body having a base portion; an objective lensswitching mechanism for switching objective lenses to position one ofthe objective lenses on the observation optical axis; a stage forcarrying a specimen; an ocular lens for observing a specimen imageobtained with said one of the objective lenses; a rough/tine motionfocusing mechanism disposed rearward of the stage, for moving theobjective lens switching mechanism along the observation optical axis inrough motion and fine motion; a first rough motion handle and a firstfine motion handle provided near the rough/fine motion focusingmechanism, for operating the rough/fine motion focusing mechanism; arough/fine motion focusing operation portion for operating therough/fine motion focusing mechanism, said rough/fine motion focusingoperation portion including a second rough motion handle and a secondfine motion handle, which are provided near a front end of the baseportion; and a linkage mechanism for linking the rough/fine motionfocusing mechanism with the rough/fine motion focusing operationportion.
 2. The microscope according to claim 1, wherein the rough/finemotion focusing operation portion is located on a front side of themicroscope, which is on a same side of the microscope as an observerposition.
 3. The microscope according to claim 1, further comprising: afirst belt provided between a rough motion shaft of the rough/finemotion focusing mechanism and a rough motion shaft of the rough/finemotion focusing operation portion, for transmitting a rotation force;and a second belt provided between a fine motion shaft of the rough/finemotion focusing mechanism and a fine motion shaft of the rough/finemotion focusing operation portion, for transmitting a rotation force. 4.The microscope according to claim 1, wherein a stopper handle isprovided on the rough/fine motion focusing operation portion, forpreventing one of said one of the objective lenses and the stage frommoving to shorten a distance between said one of the objective lensesand the stage.
 5. The microscope according to claim 1, wherein the firstrough motion handle, the second rough motion handle, the first finemotion handle, and the second fine motion handle have substantially asame structure.